le7920 Zarlink Semiconductor, le7920 Datasheet - Page 11

• Manufacturer Part Number: le7920
• Description: Subscriber Line Interface Circuit
• Manufacturer: Zarlink Semiconductor

Thermal Management Equations (Normal Active and Tip Open States)
Z
R
C
RD
C
I
P
Z
R
STANDBY
RTMG
RX
DC1
DC
CAS
P
T
TMG
SLIC
ON
=
=
=
+
250
=
≥
=
R
1.5 ms
=
------------ •
G
=
Z



------------------------------ -
3.4 10
DC2
510
-------- -
42L
--------------------------------- -
(
(
----------------------------------------------------------------------- -
I
L
V
Z
T
=
V
V
•
2WIN
BAT
BAT
I
--------------------------------- -
BAT
=
V
,
1
400 Ω
LOOP
•
(
R
----------------------------------
R
BAT
5
R
-------------- -
I
RD
--------------------------------------------------- -
Z
1250
–
LOOP
π
–
DC1
DC1
TMG
•
–
f
T
6 V
2
I
c
6 V
OFF
+
L
R
–
+
+
•
–
250
F
3 V
R
+
–
)
R
R
P
500
–
State
=
L
70
70
RTMG
DC2
DC2
(
(
415
-------- -
Z
0
1
2
3
I
I
Z
L
Ω
T
Ω
L
T
•



)
+
2
,
R
–
2
R
R
C
L
)
L
F
D
Table 2. User-Programmable Components
)
)
( )
2
=
I
•
L
0.5 ms
---------------- -
R
2
R
TMG
+
D
0.12
C2
Table 1. SLIC Decoding
0
0
1
1
W
Zarlink Semiconductor Inc.
C1
0
1
0
1
11
Z
resistors are R
impedance. When computing Z
pole and any external stray capacitance between VTX and RSN
must be taken into account.
Z
G
R
pin. R
desired loop current in the constant-current region.
R
DGND and I
off hook.
C
cut-off frequency.
Standby loop current (resistive region).
R
the SLIC in Active and Disconnect state constant-currents only.
Power dissipated in the TMG resistor, R
Disconnect states.
Power dissipated in the SLIC while in Active and Disconnect
states.
Disconnect
Ringing
Active
Standby
T
RX
DC1
D
CAS
TMG
42L
Two-Wire Status
is connected between the VTX and RSN pins. The fuse
and C
is connected from VRX to RSN. Z
, R
is the desired receive gain.
DC1
is the regulator filter capacitor and f
is connected from TMG to VBAT and saves power within
DC2
D
and R
form the network connected from R
, and C
T
is the threshold current between on hook and
F
, and Z
DC2
DC
are approximately equal. I
form the network connected to the R
2WIN
Ring trip
Ring trip
Loop detector
Loop detector
DET Output
is the desired 2-wire AC input
T
, the internal current amplifier
T
TMG
is defined above, and
c
is the desired filter
, during Active and
LOOP
D
to AGND/
is the
DC